Flowers - Up Close - EXTREME DOF Part 5

This is the fifth and I think final post about close-up photography of flowers, insects, etc...  If you haven't read the others you can live on the wild side and read this one first or go back and take them in sequence.  If DOF brings to mind Department of Finance and EXTREME makes you think we are headed for another bailout, then you really need to go back and start at the first post.

What I am going to talk about in this post is nothing short of magic.  Anyone who has worked in closeup photography knows that there are limits to what can be done with focus and DOF.  While writing the other posts I hoped that everyone understood that all I talked about carried an unspoken warning label "Within the physical limits of the lenses ability to focus".  There are definite limits to how much DOF you can get no matter how small the aperture and the limit increases as you move closer.  Sometimes the best DOF at f45 is not much thicker than a dime.

Here is an example and it is not even really extreme.  I am nowhere near 1 to 1 macro yet even at f22 the DOF will not carry across even the front flower.  Forget about sharp focus across both flowers.

As I mentioned in an earlier blog, my point of focus was about half way into the front petals.  At f22 the best I could do was to get the front petal and part of the center of the first flower into focus.

Selective focus like this can result in very beautiful images and I do it on purpose often to create soft flowing images.  This shot might even work better with a more open aperture because as I stopped down to get greater DOF I also got more background clutter.

Too bad you cannot have it all, deep DOF to fully cover your main subject AND shallow DOF to keep the background soft and unobtrusive.  Well....welcome to the wonderful world of digital!  You really can have both with a process called focus stacking.

So what is focus stacking???  It is simply a procedure where you take a series of images with different points of focus then blend them together in post processing to create one image that has impossible DOF.

All you need to do this is a calm day with little or no subject movement, a camera solidly mounted on a tripod, and post processing tools.  I use Photoshop CS4 but if you don't have Photoshop you can purchase free standing packages that do the work for you.  Helicon Focus is one of the more popular ones but there are several others.

I took 8 images and blended them together in Photoshop to create this next example.

In the first image I got the tip of the closest petal in focus then for the next 7 I carefully moved the focus point back until by the 8th image I was well back into the second flower.

Notice two things, first all of the front flower and most of the second flower are in focus, second the background is soft, much softer than in the single image shot at f22.  The reason for all the softness in this second image is that all of the 8 images were shot with the lens open to f5.6.

In addition to no subject or camera movement there are a couple of other rules.  You should shoot the images in order front to back and input them into the software in that order.  You should also be very careful to leave no out of focus areas as you move back into the subject, make sure there is overlapping DOF.  If you do not overlap the DOF you will have bands or waves of focus and unfocus which look very unnatural.  Shooting at an open aperture makes it harder to overlap the DOF and requires more images and more processing power.



Here is an example of a flower I shot at f3.5 and blended 13 images to create the final image.  Take a close look at this totally impossible depth of field.

If you have Photoshop CS4 here is how to do this. 

1.  Open Bridge and select the images to be merged, in the correct order. 
2.  Click on "Tools" --> "Photoshop" --> "Load Files into Photoshop Layers"
3.  Photoshop comes up with each image in a separate layer shown in the right side panel for Layers
4.  Select all of the images
5.  Click "Edit" --> "Auto-Align Layers"
6.  Select "Auto" and click OK
7.  When that process is complete click "Edit" --> "Auto-Blend Layers"

Auto-blending layers may take a few minutes, LOTS of processing going on here.  This step reminds me strongly of waiting for an image to come up in the black & white darkroom.  You will have an out of focus image on the screen while the computer works and then, just like magic, the image will resolve itself into something beautiful (we hope).

After all that, you will have an image that probably needs some cropping to clean up the edges and it may have some ghosting that needs cleaning up, especially if there was ANY movement of subject or camera.  You will need to flatten the layers before you can do any serious processing to the image.

Just for fun, here is one more example of the power of focus stacking:

First image is soft and flowing.  I shot it with a Nikon 105 macro wide open to f3.5.  Not very much is in focus, just a very shallow area in the center of the flower.  Background is very soft and undefined.

This second image was shot with the same lens and camera position but the aperture was stopped down to f22 to get greater DOF.

This one has most of the flower in focus but the leaves in the background are also becoming more distinct.  I liked the softer background better so this final image was a focus stack of 8 images all shot at f3.3.

I left just a little bit of ghosting around the large petal that is front and center so you could see what it looks like.  Here is the best of both worlds, I have the flower totally and impossibly in focus with the background soft and unobtrusive.

Life is good......Later!